Fruit harvesters and in particular, grape harvesters, are used to mechanically harvest grapes from grape vines. Such harvesters typically include one or more conveyors that collect the grapes loosened from the grape vines and convey the fruit to onboard storage or to other vehicles for transport from the field.
In a conventional harvester, leaves and other light materials with high surface area are separated from individual grapes and grape bunches using fans to discharge the undesirable materials other than grape (“MOG”). A conventional over the row harvester is shown in FIGS. 1A and 1B.
Normally, the use of fans to move air in order to discharge MOG with high surface area provides individual grapes and grape bunches with an acceptably low weight percentage of MOG for further processing in wineries before fermentation. However, sometimes a lower weight percentage or even complete elimination of MOG is desired to minimize or avoid additional processing time before fermentation. In order to achieve a lower weight percentage of MOG, harvesters may be equipped with additional mechanical separation systems on board the harvester. These systems may include, for example, a de-stalker system that loosens grapes from their stalks (also known as the rachis) and discards the stalks, as well as a secondary fine-material sorting system that rejects elements of MOG, such as leaf stalks (also known as petioles). One common method for fine-material sorting on board grape harvesters is a continuous perforated conveyor belt that has appropriately sized mesh openings to allow grapes to fall through the openings while leaving MOG on the surface to be discarded.
These systems operate in a satisfactory manner when the grape load is light and evenly distributed on the conveyor surface, but when heavy loads of grapes are handled, some amount of grapes may fail to pass through the perforated belt, causing a loss of harvested grapes. It would, therefore, be beneficial to provide for a system that provides improved separation of grapes and other materials and minimizes losses of harvested grapes by causing more grapes to pass through the conveyor.